Gas properties in the disc of NGC 891 from Herschel far-infrared spectroscopy

We investigate the physical properties of the interstellar gas in the nearby edge-on spiral galaxy NGC 891, using Herschel PACS/SPIRE observations of the most important far-infrared (FIR) cooling lines -[CII] 158 mu m, [NII] 122, 205 mu m, [OI] 63, 145 mu m, and [OIII] 88 mu m -obtained as part of the Very Nearby Galaxy Survey (P. I.: C. D. Wilson). We compare our observations to the predictions of a photo dissociation region (PDR) model to determine the gas density, n, and the strength of the incident FUV radiation field, G(0), on a pixel-by-pixel basis. The majority of PDRs in NGC 891's disc exhibit properties similar to the physical conditions found in the spiral arm and inter-arm regions of the face-on M51 galaxy. We estimate a stronger FUV field in the far north-eastern side than compared to the rest of the disc.